FlightAware Discussions

One antenna to feed 3 receivers flightaware + Plane Finder + Radarbox24

Hi Guys,

I have a great Spot with 360º view with an elevation above ground of 1955 feet.
The site its located right in the midle of Portugal, Vila De Rei.


The antenna is located in the comunnications tower marked in yelow.
Despite i’m about 160kms away, i have remote acess to the site, i have a 4,5Km point-to-point wireless link conecting from my parents country house to the site.
The installation have a flightaware antenna and i’m using about 30meters cable (outdor satellite tv coaxial cable, not the best cable for it as i wanted … but i was not able to get a low noise cable in time to the instalation.)
Cable characteristics :
Coaxial cable. 6,9 mm diameter. Inner conductor CCS. 128 wires. Shielding 90dB/A class. Attenuation: 17,5dB (862 MHz) / 28,5dB (2150 MHz). PE black jacket.
75 Ohm
Attenuation
dB @ 950 MHz 18,3
dB @ 1350 MHz 22,5
datasheet :

So i’m Using a flightaware pro plus stick with a raspberry py 3 and in that raspberry i have Flightaware, flightradar24…
So far so good… now comes the tricky part that i need your advise…

As this is a great place to have a ADS-B site, i have two more dedicated receivers that were offered, a Plane Finder and a Xrange2.

At the moment i have installed a simple coaxial T, in this case a combined T to have 3 ways.


This week i have tested a ordynary tv splitter as it shows in the image below.
RF13
Splitter characteristics :
3 outputs A class splitter. Passband: 5-2400 MHz. Insertion loss: 7dB (862 MHz) / 9,5dB (2300 MHz). All ports DC pass.
datasheet :


But with this set the messages decreased you can see in the daily chart

So my questions and doubts:

I) what kind of spliter should i use in this 3 way cenarium i have read good reviews about minicircuits power spliters
whound i use a spliter like this one : minicircuits ZB4PD1-2000+

II) As the cable have a big lenght shound i use a LNA near the antenna ?



SPECIFICATIONS

Passband

1090 +/- 15 MHz

Frequency … Gain

700 MHz … 7 dB

800 MHz … 5 dB

900 MHz … 0 dB

1090 MHz … 30 dB

1150 MHz … -20 dB

1200 MHz … -7 dB

NOTES

The filter uses SMA-F connectors.

Max RF Input = -15 dBm

More questions:
Adding a LNA near the antenna might be saturating the signal? … As the flightware pro stick plus have a amplifier / filter also.??
Splitting the signal with the flightware amplifiing the signal might affect the oter receivers?

What do you thing might be the best solution to share the antenna with the 3 receivers ( Raspberry with Flightware pro sick plus + Planefinder + radarbox24 )

Thanks

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Mini-Circuits makes good stuff, but I would focus on the LNA first. Actually the coax first. Those losses are huge. Even RG-6 can do better than that.

The coax T is a horrible option.

The RTL-SDR Blog LNA is very good, and cheaper, than the one you linked.

https://www.rtl-sdr.com/new-product-rtl-sdr-blog-1090-mhz-ads-b-lna/

Voce vai receber sugestoes de todos os tipos. A minha preferencia e sempre por solucoes simples e de baixo custo.

Boa sorte, e parabens pela localizacao.

2 Likes

Replacing the cable its not possible as it was installed by the Museum facilities
But thats goes to my other question.

Adding a LNA near the antenna might be saturating the signal? … As the flightware pro stick plus have a amplifier / filter also.??

Thanks

The Pro Plus is excellent, and I use it with the RTL-SDR Blog LNA, one connected to the other, no cabling. No saturation seen in my case.

If the Pro Plus is indoors, meaning, not at the antenna, the saturation risk is non existent. The RTL-SDR Blog LNA will add 27 dB gain, if I recall correctly, that will basically cover for the coax loss.

Keep in mind that bias-t is needed for the LNA. The Pro Plus does not provide that, so a cheap eBay power inserter will be needed. That may add too much trouble in your case, additional cabling and/or power connections.

If open to changing the stick, for the simplicity of eliminating the power inserter, look at this one:

https://www.nooelec.com/store/nesdr-smartee-sdr.html

You’ll lose the built-in LNA and filter, but in conjunction with the RTL-SDR Blog LNA, not a show stopper.

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It’s not a problem if the cable has some attenuation.

With that splitter it’s even less of a problem.

Do yourself a favor and get a quality LNA:
https://www.rtl-sdr.com/new-product-rtl-sdr-blog-1090-mhz-ads-b-lna/

I’d use an bias-t in front of the splitter to power the LNA and feed that with the USB voltage or even the 3.3V from the Raspberry Pi.

Edit: Oh, somehow missed it was already written :slight_smile:

1 Like

I might consider a solution like a

Mini usb Bias tee powered by the Raspberry - Coaxial Cable - and near the antena add a Uputonics 1090MHz ADS-B Filtered Preamp

Mini usb bias tee:
Mini-BIAS-TEE-1-5000MHz-USB-and-1-25V-input

Uputronics:
https://store.uputronics.com/index.php?route=product/product&product_id=50

before set it in production i will have to test it at my home

1 Like

This bias-tee inserter looks great. Is it still available somewhere? eBay does not list it right now.

If you already have one, go for it. If not, the $3 eBay ones can easily be converted to operate the same way. Actually, I should try that with the other one I have.

As for the Uptronics, it does have a loyal following. Is it better than the RTL-SDR Blog LNA? I don’t know. I once thought about getting their ceramic filter version, but never did.

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I have many Uputronics LNAs including the ceramic and non-ceramic 1090Mhz versions, UAT978Mhz, APRS 144.39Mhz and AIS 162Mhz. I did break one, but that was my fault. Too much strain SMA connector and ended up ripping it out. Some have been working well for years.

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The uputronics LNA overloads easier than the rlt-sdr blog LNA.
(or do i remember that wrong @keithma?)

So especially if there are transmitting antennas on the tower, i would recommend the rtl-sdr LNA.

Also note that if you get a splitter that shares DC among the ports, it would be better to place the bias-t on the antenna side of the splitter.

You don’t want to supply the other receivers that are connected to the splitter with DC.

1 Like